A major objective of the proposed research is to develop methods whereby the prevalence of drug abuse can be (a) accurately and economically estimated for specific drugs, population groups, and residential areas, (b) placed within a context of other health and social problems, and (c) related to social dimensions which characterize residential neighborhoods. The setting of this research in a tri-ethnic, middle-sized city in the Southwest is expected to favor the additional aims of gaining new understandings of the epidemiology of drug abuse and of developing prevalence estimates which are maximally useful in the planning of intervention programs. Based on a social area analysis at the census tract level, the city under study will be divided into demographically homogeneous areas. Within a calibration sample of these areas an intensive study will be made of the prevalence of drug use. In addition to the social area measures, the sources of data for this study will include a household survey, interviews of school non-attendees and dropouts, as well as a sample oF attendees, community panel survey, a school survey and several kinds of prevalence indicators. The last two sets of data will be available for the extended sample of geographic areas. Prevalence estimation formulas developed and validated in the calibration sample will then be applied to the more limited data of the extended sample.